Vapor generating and superheating unit



Sept. 20, 1960 DE CARR c. BRADDY 2,952,975

VAPOR GENERATING AND SUPERHEATING UNIT y d d 1 m t m m w 5 r q, My m C h8 S6 D 4 H 3 w 2m 1. 1 mul- I F Filed Nov. 15, 1957 ATTORNEY P 0, 1960DE CARR c. BRADDY 2,952,975

VAPOR GENERATING AND SUPERHEATING UNIT Filed Nov. 15, 1957 4Sheets-Sheet 2 FIG.3

2 -32 REHEATER sac. r J SPHTR o- T 35/ AIR 1o1 13 a GAS SEc. SPHTR/ 9194 9o as SPHTR 118 CYCLONE a9 I FURNACES 42 43 r I V AIR 120 4 GA$ 5VAPOR TURBINE 16 1o H TURBINE 14 COMPRESSOR 42 F" "fi FIG 9 43A STACKEcon. 40 13 94 AIRHEAT. 97

INVENTOR. 16 De Carr C. Braddy GAs Tuna.

14 VAPOR COMPRESSOR TURBINE 1 v 1 8 Ewan/ ATTORNEY Sept. 20, 1960 DECARR c. BRADDY 2,952,975

VAPOR GENERATING AND SUPERHEATING UNIT 4 Sheets-Sheet 3 Filed Nov. 15,1957 V d m RT. B T. m c Mr r a C e D ATTORNEY Sept. 20, 1960 DE CARR C.BRADDY VAPOR GENERATING AND SUPERHEATING UNIT Filed Nov. 15, 1957 4Sheets-Sheet 4 10a 103 F|G.7 FIGB 43A A t 126 k 73A 75 77A i INVENTOR.

De Carr C. Braddy BY ATTORNEY United States Patent 2,952,975? PatentedSept. 20, 1960 VAPOR GENERATING AND SUPERHEATING UNIT De Carr C. Braddy,Jamaica Estates, N.Y., assignor to The Babcock & Wilcox Company, NewYork, N.Y.., a corporation of New Jersey Filed Nov. 15, 1957, Ser. No.696,721

17 Claims. (Cl. 60-3918) This invention relates to the construction andoperation of binary elastic fluid power plants and more particularly toimprovements in the construction and operation of a fluid heating unitespecially adapted for the simultaneous generation of highly superheatedhigh pressure vapor and high temperature high pressure gases for use inthe production of power by a binary elastic fluid power plant.

In accordance with the invention, the fluid heating unit is of thesupercharged forced circulation type and is associated with a powerplant including a vapor turbine, a gas turbine and an air compressordriven by the gas turbine. The term supercharged as used herein means acombustion process wherein the pressure of the gases generated in thefluid heating or vapor generating unit is of such a magnitude thatuseful work may be done by these gases after leaving the fluid heatingunit through expansion in a gas turbine to essentially atmosphericpressure. The invention provides for a supercharged fluid heating unitwherein the fuel firing equipment is supplied with high pressure airfrom the air compressor and the vapor generating and superheatingsurfaces are specially proportioned and arranged to maintain asubstantially constant vapor temperature to the vapor turbine over arelatively wide range of vapor generation rates, while a substantiallyconstant portion of the high pressure heating gases at a substantiallyconstant temperature are delivered to the gas turbine from a particularposition in the gas flow path in the fluid heating unit and theremainder of the gases generated in the unit are recirculated for mixingwith the freshly generated gases. In addition, the construction andarrangement of the fluid heating unit of the invention provides a higherefliciency when incorporated in a combined gas turbine-steam turbinepower plant than the base steam or gas-turbine plants individually;eliminates the need for the forced and induced draft fans customarilyassociated with a vapor generating unit; and provides a compactinstallation of reduced size and weight as compared to a conventionalunit due to higher heat transfer rates resulting from high gas densityin the unit.

The invention also provides for a fluid heating unit comprising anupright vessel of substantially circular horizontal cross-section, anupright gas flow chamber of substantially rectangular horizontalcross-section containing superheating surface in the form ofhorizontally extending return bend tubes and disposed within andcooperating with the upright vessel to define an air flow spacetherebetween, with the air flow space supplied with air from the gasturbine-driven compressor at a pressure at least equal to the gaspressure in the uprigiht chamber to counter-balance the outward thrustof the heating gases exerted on the inside of the boundary walls of theupright chamber. This arrangement minimizes the need for lateral steelsupports for the boundary walls of the upright gas flow chamber,prevents blasting or leakage of the heating gases through the boundarywalls of the upright chamber, provides an optimum quantity of space inthe upright chamber for accommodation of vapor generating andsuperheating surface, and permits use of uncomplicated superheater tubearrangements.

The various features of novelty which characterize the invention arepointed out with particularity in the claims annexed to and forming apart of this specification. For a better understanding of the invention,its operating advantages and specific objects attained by its use,reference should be had to the accompanying drawings and descriptivematter in which I have illustrated and described a preferred form of myinvention.

Of the drawings:

Fig. 1 is a partly diagrammatic sectional elevation of a superchargedonce-through forced circulation steam generating unit constructed andoperable in accordance with the invention;

Fig. 2 is a sectional elevation taken along line 2-2 of Fig. 1;

Fig. 3 is a diagrammatic representation of the flow paths of thevaporizable fluid, the heating gases and the air in the binary fluidpower plant with which the fluid heating unit of Figs. 1 and 2 isassociated;

Fig. 4 is a plan view taken along the line 4-4 of Fig. 1;

Fig. 5 is a fragmentary plan View taken along the line 5-5 of Fig. 1;

Fig. 6 is a fragmentary plan section view of one of the gas by-passes ofFig. 2;

Fig. 7 is a partly diagrammatic sectional elevation of a modified fluidheating unit construction;

Fig. 8 is a sectional elevation taken along the line 8-8 of Fig. 7;

Fig. 9 is a diagrammatic representation of the flow paths of thevaporizable fluid, heating gases and air in the binary elastic fluidpower plant with which the fluid heating unit of Figs. 7 annd 8 isassociated; and

Fig. 10 is a plan view taken along the line 10-10 of Fig. 7.

In the drawings the invention has been illustrated as embodied in abinary elastic fluid power plant intended for central station use. Theparticular power plant illustrated in Figs. 1-6 has a net combinedoutput of 144,000 kw., with the steam turbine supplying 126,000 kw. andthe gas turbine 18,000 kw., which represents 12.5% of the plant rating.The bottom-supported supercharged forced flow once-through steamgenerating unit is designed on coal firing for a maximum continuoussteam output of 800,000 lbs. of steam per hr. at a pressure of 3550 psi.and a total temperature of 1050 F. at the superheater outlet, a maximumcontinuous steam output of 685,000 lbs. of steam per hr. at a pressureof 530 p.s.i. and a total temperature of 1000 F. at the reheater outlet,and a maximum continuous gas discharge from the steam generating unit tothe gas turbine of 1,075,000 lbs. of gas per hr. at a temperature of1450 F. and a pressure of 83 p.s.i.a. While the fluid heating unitconstructions illustrated and hereinafter described are specificallydesigned and particularly adapted for burning coarsely pulverized orgranulated bituminous or semibituminous coal in a cyclone type furnace,it will be understood that the fluid heating units illustrated may alsobe fired by other types of solid fuel burners or by various types ofliquid or gaseous fuel burners.

In the binary elastic fluid power plant illustrated in Figs. 1-6, acompressor 10, driven by a gas turbine 11, discharges air at a pressureof about 88 p.s.i.a. through an airheater 12 to a supercharged forcedflow once through fluid heating or steam generating unit .13. Allcombustion takes place in the fluid heating unit 13, and steam isgenerated at supercritical pressures and temperatures. It will beunderstood, however, that the fluid heating units illustrated andhereinafter described may also be advantageously used for steamgeneration at subcritical pressures and temperatures. The fluid heatingunit is constructed and arranged to deliversteam tothe high and lowpressure stages of a vapor or steam turbine 14, while passing highpressure high temperature gases to the gas turbine 11. To maintain highplant efliciency at low steam generation rates, the, gas turbine poweris kept near maximum over a wide'range of steam' generation rates on thefluid heating unit by maintaining a substantially constant gas flow tothe turbine 11, while Ve ying the fuel rate to the fluid heating unit,and maintaining the gas temperature to the gas turbineand thesteamtemperatures tothe steam turbine at substantially, constant values. Thevapor turbine 14 drives.an electric generator- 1 .and the gas turbine 11;drive's"an.electric generator 16,'as well as the compressor 10. Heatfrom the gas turbine exhaust is recovered by passing the gases over theairheater 12 to preheat the'compressor discharge air before flowing tothe fluid heating unit 13; and over an economizer 16 to partially heatthe feedwater for the fluid heating unit 13. V

In accordance with the invention," and particular reference totheembodimentofEigs; l 6, the fluid heating unit comprises an uprightinsulation covered metallic vessel 17 of substantially circularhorizontal cross-section; an upright chamber 18 of substantiallyrectangular horizontal cross-section having .a,,;lower,. furnace chamberportionA and an upper convection gas cooling chamber portion B definedby a front wall 19, a rear wall 20, and opposing sidewalls 21, 22 anddisposed within, and cooperating with the vessel -17 todefine an airflow space 23 therebetweenjand a fuel firing section consisting of apair of in'depen'dently operable horizontally extending cyclone typefurnaces 24, 25 of relatively small volume and boundary wall areadisposed at the same level on opposite walls 19 and 20 at the lowerportion of the chamber-A,- arranged. to burn a solid fuel at high ratesof heat release, and separately discharging high temperature gaseousproducts of combustion and separated ash residue as a molten slag intothe lower portion of the chamber A. A secondary superheater 26 occupiesthe lower and central portions of the chamber B. Parallel gas passes27,28 and 29, 30 are provided in the upper portion of the chamber B and thevessel 17, respectively, the passes 27 and 28 being occupied by areheater 31 and another secondary superheater 32, respectively, and thepasses 29 and 30 being gas by-passed around the reheater 3 1 andsuperheater 32. A vertically elongated insulation covered metallicvessel 33 of substantially circular horizontal cross-section is.disposed laterally adjacent the vessel 17. An upright gas pass 34 ofsubstantially rectangular, horizontal cross-section is disposed withinand cooperates with the vessel 33 to define an air flow space 35therebetween. A primary superheater 36 occupies the upright gas pass 34.An upwardly extending insulation covered metallic conduit 37 ofsubstantially circular horizontal cross-section is connected at one endand opens to the upper portion of the vessel 17 and is connected at'itsopposite end to the upper end of the vessel 33. An upwardly extendingmetallic conduit 38 of substantially circular cross-section isconcentrically disposed within and cooperates with the conduit 37 todefine'a'n annular air flow space 39 therebetween communicating at oneend with the air flow space 23 and at its opposite end with the air flowspace 35. The con duit 38 is connected at its upper or gas inlet end andopens to the upper portion of the chamber B through the side wall 22thereof at a position downstream gas-wise of the parallel gas passes 27,28 and is connected at its lower or gas discharge end to the upper orgas inlet end of the upright gas pass 34 by a transitiontconduit 38A.The intake to the gas turbine 11 is connected to the chamber B by aninsulation covered metallic conduit 40 of, substantially circularcross-section extending through the vessel 17 in sealing relationtherewith and opening to the chamber B through the'side wall 21 thereofat the same level as the gas inlet to the conduit 38. The connections ofthe conduits 38 and 40 to the walls 22 and 21, respectively, areprovided by slip type expansion joints 41 to allow for ditferentialvertical expansion between the vessel 17"and the chamber 18 andintermediate portions of the conduits 38 and 40 are provided withbellows type expansion joints to permit vertical expansion thereof. Agas recirculation fan '42 has its intake connected to the lower end oftheupright gas pass 34 by a conduit 43 having a bellows type expansionjoint 44 and its discharge connected to the chamber A by an insulationcovered conduit 45 of circular cross-section extending through thevessel 17 in sealing relation therewith and opening to the chamber Athrough the rear wall 20 thereof at a position superjacent the cyclonefurnaces and between the cyclone furnacesand the sec ondary superheater26. The conduit 45 is provided with a pair of spaced bellows typeexpansion joints 46 adjacent its discharge end. 'I'helowerend of thevessel 33 is formed with a dished wall 47 having an opening thereinthrough which the conduit 43 extends in sealing relation therewith. i 7V c J 7 Each cyclone furnace 24, 25 comprises a horizontally elongatedcombustion chamber 49 of substantially circular cross-section," thecircular boundary wall being formed by oppositely arranged groups ofrefractory covered closely spaced studded tubes 50, the tubes 50 alongone side having their lower ends-alternately connected to lower headers51 and 52 and their upper ends connected to a header 53 and the tubes50along the opposite side having their lowenendsalternately connected tolower headers 54 and 55 and their upper ends connected to a header 56.The upper and lower ends of each tube 50 are reversely bent,andopposite-tubes at the top of each: combustion chamber spaced aparttoform a tangentially arranged secondarycombustion air inlet 57 extendingover a major portion of the length of the chamber. The front or outerend of each combustion chamber 49 is closed by a frusto-conical wallsection 58 including refractory covered closely spaced studded tubesextending between horizontally. arranged top and bottom headers 60 and61, respectively, and havi-ng their intermediate portions curved todefine a circular fuel inlet port 62. A fuel inlet conduit 63 registerswith the port 62 and is arranged to discharge a whirling stream ofprimary combustion air and crushed coal through the port 62. The rear orinner 'end of each'combustion chamber is partially closed by :fluidheating tubes of the front and rear walls 19 and 20, respectively,intermediate portions of some of these tubes being bent to form aninwardly projecting igas outlet throat 64 and a slag outlet 65 for eachcombustion chamber.

In cyclone furnace 24 the header 61 issupplied with feedwater by tubes66, the headers 51, 52 and 54, 55 are connected for flow of fluid fromthe header 60 by tubes 67, and the headers 53 and 56 are connected forflow of fluid to the inlet header 61 of cyclone furnace 25 by tubes 69.In cyclone furnace 25 header 60 is connected for fluid flow to theheaders 51, 52 and 54, 55 by tubes 67. i

Each boundary wall of the upright chamber 18 is formed by fluid heatingtubes having their intertube spaces closed by metallic webs 7 1, asshown in Figs. 5 and 6, welded to the tubes :along the lengthsthereof toprovide a gas-tight enclosure, thetubes of the front wall 19 havingtheir opposite ends connected to headers 72 and 73, the tubes of therear wall 20 having their opposite ends connected to headers 74 and 75,the tubes of-side wall 21 having theiropposite ends-connected to headers76 and 77, and the tubes, :of side wall 22' having their opposite endsconnected to headers.78 and 79. The tubes ofreach 'boundarywall of theupright chamber 18 are arranged for parallel flow of'fluid relative tothe other boundary walls thereof and are supplied with fluid by tubes 88extending from the headers 53 and 56 of the cyclone furnace to thesupply headers 72, '74, 76 and 78. The tubes of the fiont and rear Walls19 and 20 have their lower portions bent inwardly and downwardly todefine in conjunction with the side walls 21, 22 a rectangular throatpassage 81 for discharging molten slag into a slag tank 82. The tubes ofthe side walls 21, 22 have their upper portions bent inwardly andupwardly in converging relation, with the space at the point ofconvergence sealed with suitable refractory material. Alternate tubes ofthe front and rear walls 19 and 20 are bent laterally and inwardly atpositions subiacent and superjacent the gas passes 27, .28 to providegas inlets and outlets 83, 84 and 85, 86 to the gas by-passes 29 and 30,respectively. Gases passing through the outlets 84 and 86 discharge intothe portion of chamber B from which gases flow to the conduits 38 and40. At the top of the chamber B the tubes of the front and rear walls 19and 20 are formed with retlun bends from which tubes 19A and 20A havingtheir intertube spaces closed by metallic webs extend downwardly in theair flow space 23 in spaced relation and parallel to the front and rearwalls 13 and 20 to define in conjunction with the front and rearboundary walls the gas by-passes 29 and 30, respectively. An uprightgas-tight metallic baffle 87 cooperates with the enclosure walls of thechamber B to define the gas passes 27 and 28. Intermediate portions ofsome of the boundary wall tubes of the chamber 18 are bent to form theopenings with which the gas outlet of the conduit 45 and the gas inletsof the conduits 38 and 40 register.

Substantially all of the space available in the chamber B and theupright gas pass 34 is effectively employed for heat transfer, thisspace being occupied by steam superheating and reheating surface in theform of banks of horizontally arranged serially connected return bendtubes disposed across the path of the heating gases. The upright gaspass 34 is occupied by the primary superheater 36 which comprises banksof top-supported multilooped horizontally extending tubes arranged inlaterally spaced panels and having their opposite ends connected tohorizontally extending inlet and outlet headers 89 and 90 disposed inthe air flow space 35, with corresponding panels serially connected todefine parallel paths for fluid flow between the headers 89 and 90 incounter flow heat transfer relation with the gases. The space from thegas inlet of the chamber B to a position subjacent the gas inlets 83, 85is occupied by the secondary superheater 26, the tubes of which arearranged similar to those of the primary superheater, except that thelateral spacing of the tube panels in th two lower banks thereof isdouble that of the upper banks and the tubes are arranged in parallelflow heat transfer relation with the gases, and have their opposite endsconnected to horizontally extending inlet and outlet headers 91 and 92,respectively, situated in the air flow space 23.

The primary superheater 36 is connected for series flow of fluid fromthe boundary walls of the chamber 18 by tubes 93 extending between theinlet header 89 and the headers 73, 75, 77, and 79 and for series flowof fluid to the secondary superheater 26 .by tubes 94 extending betweenthe outlet header 0 and the inlet header 91. The tubes of the secondarysuperheater 32 occupy the gas pass 23, are arranged similar to those ofthe primary superheater 3 's and for fluid flow in counter flow heattransfer relation with the gases, and have their opposite ends connectedto horizontally extending inlet and outlet headers 95 and 96,respectively, disposed in the :air flow space 23. The secondarysuperheater 32 is connected for series flow of fluid from the secondarysuperheater 26 by tubes 97 extending between the outlet header 92 andthe inlet header 95. Fluid discharging from the outlet header 96 passesto the vapor turbine 14 by way of a conduit 98.

The gas pass 27 is occupield by the reheater 31, the

tubes of which are arranged similar to those of the super heater 32 andfor fluid flow in counter flow heat transfer relation with the gases andhave their oppositeends connected to horizontally extending inlet andoutlet headers 99 and 1011, respectively, disposed in the air flow space23. The reheater 31 is connected for series flow of fluid from the vaporturbine 14 by a conduit 101 and to the low pressure stage of the turbine14 by way of conduits 102 leading from the outlet header 100. Suitableseals are provided between the vessel 17 and the conduits 101, 102 attheir points of passage through the vessel 17.

The upper end of the vessel 17 is closed by an inverted dished wall 103and the lower end is formed with a dished wall 104 having an openingtherein through which the upper portion of the slag tank 82 extends insealing relation therewith. A horizontally extending insulation coveredmetallic cylindrical vessel 105 is concentrically arranged about eachcyclone furnace and opens at one end to the vessel 17 to define incooperation with the cyclone furnace an annular space 106 communicatingwith the air flow space 23 in the vessel 17. The opposite or outer endof each vessel 105 is formed with a dished wall 107 having an openingtherein through which the fuel inlet conduit 63 extends in sealingrelation therewith.

The fluid heating unit 13 is bottom-supported by structural steelmembers including upright members 108, ribbed annular skirts 109 and 110secured to the upper ends of the upright members 108, and ribbed annularskirts 111 and 112; adjacent the bottom of the vessels 17 and 33,respectively, snugly-fitted and welded to the outer sides thereof andsuitably secured to the annular skirts 109 and 110, respectively. Thesestructural members are of sufficient size and strength to bottom supportthe entire load of the fluid heating unit. All of the boundary walls ofthe upright chamber 18, as Well as the superheating and reheatingsurfaces therein, are pendently supported from horizontally disposedsteelwork including ribbed annular skirts 125 and 126 at the top portionof the vessel 17 welded and snugly-fitted to the inner and outer sidesthereof and cross members such as 113 and 114 carried by the skirt 126.Steel-work for pendently supporting the gas pass 34 and the primarysuperheater disposed therein includes annular ribbed skirts 115 and 116at the top portion of the vessel 33 welded to the inner and outer sidesthereof and cross beams 117 carried by the skint 116 and from whichsuitable hangers support the primary superheater. Thus the describedsupport arrangement provides for upward expansion of the Vessels 1 7 and33, while the boundary walls of the chamber 18 and the gas pass 34 andthe superheating and reheating surfaces expand downwardly.

For the sake of clarity, Fig. 3 diagrammatically shows the flow paths ofthe vaporizable fluid, the air for combustion, and the heating gases forthe embodiment of the invention illustrated in Figs. 1 and 2. Feedwaterat a pressure of 4500 psi. is supplied by a feed pump, not shown,through feedwater heaters, not shown, using steam bled from the turbine14 at appropriate stages in the turbine. The partially heated feedwaterthen passes through the economizer 16 and tubes 66 to the inlet header61 of cyclone furnace 24. While Fig. 3 diagrammatically illustrates thatthe water then passes successivelythrough the wall-cooling tubes of thecyclone furnaces 24 and 25 to the boundary wall supply headers of thechamber 18, the particular path of the water through the cyclonefurnaces is best seen in Figs. 1 and 2. With reference to cyclonefurnace 24, water discharging from the header 61 flows through the tubeslining the frustoconical section 58 to the header 60, then passesthrough tubes 67 to the headers 51, 52, 54, 55 for flow through walltubes 50. Headers 53 and 56 receive water from the wall tubes 50 anddischarge to the inlet header 61 of the cyclone furnace 25 by way oftubes 69. Circulation in and the front and rear walls 19 and 20,including the tube portions 19A and 20A, respectively, to the boundarywall outlet headers 73, 75, 77 and '79, from whichthe water passes tothe inlet header 89of the primary superheater 36 by way of tubes 93. Thefluid heatingsu'rfaces in the cyclone furnaces and the boundary walls ofthe upright chamber 18 are proportioned and arranged so-that the portionof the heated fluid circuit in which the transition of the water from aliquid to a vapor condition occurs will be located in the relatively lowtemperature primary superheater '36 throughout the operatlng range ofthe fluid heating unit. Steam discharges from the tubes of the primarysuperheater into theoutlet header 90, then passes through tubes 94 tothe inlet header 91 of the secondary superheater 26. The tubes of thesecondary superheater 26 discharge to the header 92, from which steampasses through tubes 97 to the inlet header 95 of the finishing orsecondary superheater 32. The steam receives its final superheating inthe tubes of the super heater 32 and is discharged to the outletheader96, from which :it passes through conduit'98 to the turbine 14 forpartial expansion therein. Steam passes from the turbine 14 throughconduit 101 to the inlet header 99 of the reheater 31, then flowsthrough the tubes of the reheater to the header 100, from which itreturns to the turbine 14 through the conduits 102 for final expansion.

Combustion air is supplied by the compressor 10 at a pressure of about88 p.s.i.a. and temperature of 460 F. through the air heater 12, whichis preferably of the tubular type, to the air flow space 35 at about 600F. by way of-a conduit 120 having its discharge end registering with acircular flanged opening 121 in the vessel 33. The air flows upwardlythrough the spaces 35 and 39 in counter flow relation to the gasespassing through the conduit 38 and the gas pass 34, then enters the airflow space 23 for flow downwardly therethrough to the secondary airinlet 57 of each cyclone furnace in counterflow relation to the gassespassing through the chamber 18. Thus the air is further heated inpassing through the spaces 35, 39 and 23, since it cools the boundarysurfaces of the upright gas pass 34, the conduit 38 and the chamber 18before entering the secondary air inlets 57 at a temperature of around620 The air flow spaces 35, 39 and 23 are normally under an air pressureabout 2-3 p.s.i. higher than the heating gas pressure at any point alongits flow path, largely due to the pressure drop of the gases in flowingthrough the cyclone furnaces, so that any leakage through the boundarywalls of the chamber 18, the conduit 38 or the gas pass 34 is inwardtoward the gas flow path rather than outward to avoid the blasting ofhot gases on the walls of the vessels 17 and 33 and the conduit 37.Thus, the outward thrust of the heating gases on the inside of theboundarywalls of the upright gas pass 34, the conduit 38 and the chamber18 is counter balanced by the thrust of the air acting on the outside ofthe same boundary walls, resulting in a differential thrust of only afew pounds and minimizing the need for lateral steel supports orhorizontal buckstay members on these boundary walls to prevent warpingor. buckling thereof. In addition, the counter balancing eflect of theair on the outward thrust of the gases permits thechamber 18 and the gaspass 34 to be of substantially rectangular cross-section, as shown inFig. 4, thereby making available optimum space for accommodation ofheating surfaces and permitting use of superheater and reheater tubearrangements free from complexity. The vessels 17 and 33 and the conduit37 are advantageously of circular form in horizontalcross-section tobest withstand the outward thrust of the air on the inner surfacethereof with a minimum of lateralsupports, while providing a compactinstallation.

Since the gas turbine power is maintained substantially constant over awide range of steam generation rates, the compressor air flow will alsobe constant over this range. Thus at steam loads less than full load thecompressor air flow rate will be in excess of that required for completecombustion of the fuel. While the entire air flow from the compressor atsteam loads less than the full load may be passed to the cyclonefurnaces, alternatively the air in excess'of that needed for completecombustion of the fuel may be 'regulably withdrawn from the conduitthrough a dampered conduit 118 and discharged into the conduit-45 at theoutlet portion thereof for flow into the chamber A with the recirculatedgases.

In the normal operation of the fluid heating unit described at pressuresand temperatures above the critical values, primary air and -arelatively coarse crushed fuel in suspension is supplied to the cyclonefurnaces through the fuel inlets 63 from independently controllablesources and the fuel burned in the cyclone furnaces at high rates ofheat release suflicient to maintain-a normal mean temperature thereinabove the fuel ash fusion temperature. The secondary combustion air issupplied in quantities insuring substantially'complete combustion of thefuel in the cyclone furnaces. The ash separates as a molten slag whichflows through the outlet 65 of each cyclone furnace into the chamberA'and is discharged through the outlet 81 into the slag tank 82, whilegases with a relatively small amount of slag particles in suspensiondischarge through the;throats 64 into the lower portion of the chamberA. The gases then flow upwardly through the chamber A to the'inlet ofthe chamber B. The inside of the lower portion of the enclosure walls ofthe chamber A is covered with refractory to reduce the heat inputthereto, to maintain temperatures in this chamber portion above the ashfusion temperature so that slag .will continuously pass through thethroat 81 in a molten condition, and to withstand the high'temperatureconditions in this chamber portion.

The temperature of the heating gases flowing through the chamber portionA is regulated to provide a gas temperature at the entrance of thechamber portion B of a degree which will insure any slag particles insuspension in the gases being in a solidified or dry condition, avoidoverheating and plugging of the tubes in the secondary superheater 26,and yet provide a heat content of the heating gases suificient to attainthe desired final superheat and reheat temperatures. For this purpose,gases withdrawn by the recirculating fan 42 from the gas outlet of thegas pass 34 by way of the conduit 43 are passed through the conduit 45into the chamber A. At steam loads less than full steam load, air inexcess of that required for complete combustion of the fuel may bedelivered to the cyclone furnaces or regulably by-passed in whole or inpart through the conduit 118 to the conduit 45 for discharge into thechamber A with the recirculated gases. The recirculated gases andby-passed air enter at suflicient velocity to insure an intimate mixingwith the fresh combustion gases passing upwardly through the chamber A.The gas temperature leaving the chamber- A is controlled by variationsin the rate of fuel firing and by the quantity of gaseous fluidsintroduced into the chamber A by way of the conduit 45. The flow ofrecirculated gases is at a maximum at full steam load and progressivelydecreases as the steam load decreases. If all the air in excess of theburner requirements is bypassed through the conduit 118 to the conduit45, the quantity thereof is at a minimumat'full steam loadandprogressively. increases as the steam load decreases.

The tempered heating gases at the desired temperature flow verticallyover and between the tubes, of the sec: ondary superheater 26 and thenenter the parallel gas passes 27, 28, 29 and 30, the proportioning ofthe gas flow to these passes being regulated by dampers 122, 123, 124and 125, respectively, to control the final steam temperature leavingthe reheater 31 and the superheater 32 and the temperature of the gasespassing to the gas turbine 11. The superheating and reheating surfacesare proportioned and arranged to provide the required final or outletsteam temperatures at full steam load with no gas flow through thepasses 29 and 30. Gas flow through the passes 29 and 30 is increased asthe rate of steam generation decreases to hold the reheater 31 andsuperheater 32 outlet steam temperatures constant over a wide range ofsteam loads, while maintaining the temperature of the combined gasesleaving the passes 27, 28, 29 and 30 at a substantially constant valueof 1450 F.

Gases flowing through the parallel gas passes merge in the upper part ofthe chamber B, from which a portion Of the gases discharge through theconduit 40 to the gas turbine 11 at a pressure of about 83 p.s.i.-a. andtemperature of approximately 1450" F. and the remainder of the gasespass to the inlet of the gas pass 34 by way of the conduit 38. Theproportion of gases passing to the gas turbine 11 and the gas pass 34 iscontrolled by dampers 126 in the conduit 40, the quantity of gases atconstant temperature passing to the turbine 11 being maintained constantover a wide range of steam generation rates, this range extending fromabout one third to full steam load, while the quantity of gases passingto the gas pass 34 and thence to the chamber A progressively decreaseswith decreasing steam load from a maximum at the full rate of steamgeneration.

The portion of the gases passing to the gas turbine 11 dischargetherefrom at a temperature of about 928 F., then flow over the airheater12 and the economizer 16 to the stack at a temperature of about 325 F.The portion of the gases discharging through the conduit 38 to the gaspass 34 flow over and between the tubes of the primary superheater 36and then are withdrawn by the gas recirculation 'fan 42 for return tothe chamber A at a temperature of approximately 850 F., as previouslydescribed.

In the embodiment of the invention illustrated in Figs. 7-l0, theconstruction and arrangement of the fluid heating unit is generally thesame as that shown in Figs. 1-6, except in the particulars hereinafterdescribed, and accordingly for convenience and clarity the samereference characters are utilized to identify identical or closelysimilar parts. In the modified form, the chamber B is extendedvertically upwardly to accommodate the primary superheater 36 and theupright vessel 17 is extended vertically upwardly to define with thechamber B an extension of the air flow space 23 and to accommodate thegas recirculation fan 42 and its associated supporting steelwork. Withthe chamber B so extended, the reheater 31 and the superheater 32 occupythe central portion thereof. Upright gas-tight baflies 87A cooperatewith the enclosure walls of the chamber B to define three parallel gaspasses 27, 28 and 13%, pass 27 being occupied by the reheater 31, pass28 by the superheater 32, and the pass 130 being a gas by-pass aroundthe reheater 31 and superheater 32. Dampers 122, 123 and 132 control gasflow through the gas passes 27, 28 and 130, respectively. The banks ofsuperheater and reheater tubes are of the same construction and form asthose of the first embodiment,

except that the tube panels of the reheater 31 and super-.

heater 32 are arranged in planes normal to the planes of thecorresponding tube panels illustrated in Figs. 1 and 2. The upper endsof the front, rear and side Walls 19, 20, 21 and 22 are connected tohorizontally arranged headers 73A, 75A, 77A and 79A, respectively,disposed at the same elevation.

The conduit 40 connec g the gas turbine 11 to the chamber B opens to thechamber B at a position intermediate the primary superheater 36 and theparallel gas passes 27, 28, 136. The gas recirculation fan 42 has itsintakes connected to the upper end of the chamber B by a conduit 43A andits discharge connected to the chamber A by an insulation coveredconduit 45A of circular crosssection extending through the vessel 17 insealing relation therewith and opening to the chamber A through the sidewall 22 thereof at a position between the cyclone furnaces and thesecondary superheater 26. Thus the conduits 40 and 43A receive gasesfrom the same relative positions in the heating gas flow path as thecorresponding conduits in the first embodiment.

The vessel 17 includes a circular flanged opening 121A which registerswith the discharge end of the air supply conduit 120. As shown in Fig.10, the air flow space 23 is divided into two halves along thecenterline of the fluid heating unit by vertical baflies 138 disposedand closing the space between the vessel 17 and the chamber 18 from aposition subj-acent the opening 121A to the upper end of the chamber 18and secured along their lengths to diagonally opposite corners or" thechamber 18. The lower ends of the baffles 138 are connected to ahorizontal baflle 148 disposed and closing the space between the vesseland the chamber 18 and secured to the rear wall 20 and the sidewall 22.The baflies 138 and 140 cooperate to direct incoming air upwardlythrough one half of the air flow space 23, then downwardly through theremaining half of the space 23 to the secondary air inlet 57 of eachcyclone furnace.

The fluid heating unit is bottom-supported by structural steel membersincluding upright members 108, skirt 109, and ribbed annular skirts 111and 142 snugly-fitted and welded to the inner and outer sides of thevessel 17 at a position intermediate the baflie 149 and the cyclonefurnaces, with the skirt 111 being suitably secured to the skirt 1091.The general arrangement of the structural supports for the uprightchamber 18 and the heating surfaces contained therein is the same as inthe first embodiment. Steelwork for supporting the fan 42 includesribbed annular skirts 144, 14-6 Welded to the inner and outer sides ofthe vessel 17 and cross beams 148 carried by the skirt 144.

As illustrated in Fig. 9, the tubes of the cyclone furnaces, theboundary walls of the chamber 18 and the superheaters and reheater areconnected for serial flow of the vaporizable fluid therethrough in thesameorder as that of Fig. 3; and the superheaters and the reheateroccupy the same relative positions in the heating gas flow path and arearranged for fluid flow in the same heat transfer relations with theheating gases as the corresponding apparatus in the first embodiment.

While in accordance with the provisions of the statutes, I haveillustrated and described herein a specific form of the invention nowknown to me, those skilled in the art will understand that changes maybe made in the form of the apparatus disclosed without departing fromthe spirit of the invention covered by my claims, and that certainfeatures of the invention may sometimes be used to advantage without acorresponding use of the other features.

What is claimed is:

l. A fluid heating unit for use in a binary elastic fluid power plantincluding a gas turbine, an air compressor driven by the gas turbine anda vapor turbine, comprising walls including fluid heating tubes definingan upright chamber, means for supplying a vaporizable fluid to saidfluid heating tubes, burner means for supplying heating gases to saidchamber for flow therethrough, means for supplying air from saidcompressor to said burner means, means forming at least a pair ofparallel passes for the gases flowing through said chamber, asuperheater having at least a portion thereof in one of said parallelpasses, said superheater being connected for series flow of fluid fromsaid fluid heating tubes and to the vapor turbine, another of saidparallel passes being a gas by-pass around the superheater in said onepass, and means for 11 a maintaining a predetermined vapor temperatureto the vapor turbine over a wide range of vapor turbine power output,while maintaining a substantially constant rate of gas flowat asubstantially constant gas temperature to said gas turbine including gasturbine supply means for conducting heating gases from a positiondownstream gas-wise of said parallel gas passes to said gas turbine, gasrecycling means constructed and arranged to conduct heating gases from aposition downstream gas-wise of said parallel gas passes to said uprightchamber at a position upstream gas-wise of said superheater for mixingwith the 'freshly generated heating gases, and means for proportioningthe total gas flo-w between said parallel gas passes. i r

2. A supercharged fluid heating unit for use in a binary elastic fluidpower plant including a gas turbine, an air 7 compressor driven by thegas turbine and a vapor tur bine, comprising walls defining an uprightvessel, walls including fluid heating tubes defining an upright chamberdisposed 'at least in part within said vessel and cooperating with saidvessel to define an air flow space therebetween, means for supplying avaporizable fluid to said fluidheating tubes, burner means communicatingwith said air flow space for supplying heating gases to said chamber forflow therethrough, means conducting air from said compressor to said airflow space for flow therethrough to said burner means at a pressure atleast equal to the gas pressure in said upright chamber, means formingat least a pair of parallel passes for the gases flowing through saidchamber, a superheater having at least a portion thereof in one of saidparallel passes, said superheater being connected for series flow offluid from said fluid heating tubes and to the vapor turbine, another ofsaid parallel pases being a gas by-pass around the superheater in saidone pass, and means for maintaining a predetermined vapor temperature tothe vapor turbine over a wide range of vapor turbine power output, whilemaintaining a substantially constant rate of gas flow at a substantiallyconstant gas temperature to said gas turbine including gas turbinesupply means for, conducting heating gases from a position downstreamgas-wise of said parallel gas passes to said gas turbine, gas recyclingmeans constructed and arranged to conduct heating gases from a positiondownstream gas-wise of said parallel gas passes to said upright chamberat a position upstream gas-wise of said superheater for mixing with thefreshly generated heating gases, and means for proportioning the totalgas flow between said parallel gas passes.

3. A supercharged once-through forced flow fluid heating unit for use ina binary elastic fluid power plant including a gas turbine, an aircompresser driven by the gas turbine and a vapor turbine, comprisingwalls defining an upright vessel, walls including fluid heating tubesdefining an upright chamber disposed within said vessel and cooperatingwith said vessel to define an air flow space therebetween, means forsupplying a vaporizable fluid to said fluid heating tubes, burner meanscommunicating with said air flow space for supplying heating gases atsuperatmospheric pressure to the lower part of said chamber for flowtherethrough, means for conducting air from said compressor to said airflow space for flow therethrough to said burner means at a pressure atleast equal to the gas pressure in said upright chamber, meansforming atleast a pair of parallel passes at a position downstream gas-wise ofsaid burner means for the gases flowing through said chamber, asuperheater having at least a portion thereof in one of said parallelpasses, said superheater being connected for series flow of fluidrfrornsaid fluid heating tubes and to the vapor turbine, another of saidparallel passes being a gas by-pass around the superheaterin said onepass, and means for maintaining a predetermined vapor temperature to thevapor turbineover a wide range of vapor turbine power output, 'whilemaintaining -a substantially constant rate of gas flow at asubstantially constant gas temperature to said a a l 12 gas turbineincluding gas turbine supply means for conducting heating gases fromsaid upright chamber from a position downstream gas-wise of saidparallel gas passes to said gas turbine, gas recycling means constructedand arrangedto'conduct heating gases from a position downstream gas-wiseof said parallel gas passes to said upright chamber 'as tempering gasesat a position between the burner means and said superheater for mixingwith the freshly generated heating gases, and damper means forproportioning the total gas flow between said parallel gas passes. a

4. A fluid heating unit for use in binary elastic fluid powerplantincluding 'a gas turbine, an' air compressor driven by the gasturbineanda vapor turbine, comprising walls including fluid heatingtubes defining an upright chamber, means for supplying arvaporizablefluid to said fluid heating tubes, burner means forsupplying heatinggases to said chamber .for flow'therethrough, means for supplying airfrom said compressor to said burner means, means forming at least apair'of parallel passes for the gases flowing through said chamber, asuperheater having at least a portion thereof in one of said parallelpasses, said superheater being connected for seriesflow of fluid fromsaid fluid heating tubes and to the vapor turbine, another of saidparallel passes being a gas by-pass around the superheater in said onepass, gas turbine supply means for conducting heating gases from aposition downstream gas-wise of said parallel gas passes to said gasturbine, gas recycling means constructed and arranged to conduct heatinggases from a position downstream gas-wiseof said parallel gas passes tosaid upright chamber at a position up-stream gas-wise of saidsuperheater for mixing with the freshly generated heating gases, andmeans for proportioning the total gas flow between said parallel gaspasses. I

5. A supercharged fluid heating unit for use in a binary elastic fluidpower plant including a gas turbine, an air compressor driven by the gasturbine and a vapor tur-' bine, comprising walls defining an uprightvessel, walls including fluid heating tubes defining an upright chamberdisposed at least in part .within said vessel and cooperating with saidvessel to define an air flow 'space therebetween, means for supplying avaporizable fluidtto said fluid heating tubes, burner meanscommunicating with said air flow space for supplying heating gases tosaid chamber for flow therethrough, means for conducting air from saidcompressor to said air flow space for flow therethrough to said burnermeans at a'pressure at least equal to the gas pressure in said uprightchamber, means forming at least a pair of parallel passes for the gasesflowing through said chamber, a superheater having at least a portionthereof in one of said parallel passes, said superheater being connectedfor series flow of fluid from said fluid heating tubestand to the vaporturbine, another of said parallel passes being a gas by-pass around thesuperheater in said one pass, gas turbine supply means for conductingheating gases from a position downstream gaswise of said parallel gaspasses to said gas turbine, gas recycling means constructed and arrangedto conduct heating gases from a position downstream gas-wise of saidparallel gas passes to said upright chamber at a position upstreamgas-wise of said superheater for mixing with the freshly generatedheating gases, and means for proportioning the total gas flow betweensaid parallel gas passes.

6. A supercharged once-through forced flow fluid heating unit for use ina binary elastic fluid power plant including a gas turbine, an aircompressor driven by the gas turbine and a vapor turbine, comprisingwalls defining an upright vessel, walls including fluid heating tubesdefining an upright chamber disposed at least in part within said vesseland cooperating with said vessel to define an air flow spacetherebetween, means for supplying a vaporizable fluid to vsaid fluidheating tubes, burner means communicating with said air flow space forsupply ing heating gases at superatmospheric pressure to the lower partof said chamber for flow therethrough, means for conducting air fromsaid compressor to said air flow space for flow therethrough to saidburner means at a pressure at least equal to the gas pressure in saidupright chamber, means forming at least a pair of parallel passesdownstream gas-wise of said burner means for the gases flowing throughsaid chamber, a superheater having at least a portion thereof in one ofsaid parallel passes, said superheater being connected for series flowof fluid from said fluid heating tubes and to the Vapor turbine, anotherof said parallel passes being a gas by-pass around the superheater insaid one pass, gas turbine supply means for conducting heating gasesfrom a position downstream gas-wise of said parallel gas passes to saidgas turbine, gas recycling means constructed and arranged to conductheating gases from a position downstream gas-wise of said parallel gaspasses to said upright chamber at a position upstream gas-wise of saidsuperheater for mixing with the freshly generated heating gases, andmeans for proportioning the total gas flow between said parallel gas.passes.

7. A fluid heating unit comprising walls defining an upright vessel ofsubstantially circular horizontal crosssection, walls including fluidheating tubes defining an upright chamber of substantially rectangularhorizontal cross-section disposed at least in part within said vesseland cooperating with said vessel to define a space therebetween for airunder pressure, means for supplying a vaporizable fluid to said fluidheating tubes, burner means for suplying heating gases to said chamberat a pressure at least as great as a plurality of atmospheres for flowtherethrough, means for supplying air to said space at a pressure atleast equal to the gas pressure in said upright chamber, and asuperheater including horizontally extending return band tubes disposedin said upright chamber at a position downstream gas-wise of said burnermeans and transversely of gas flow through said chamber, saidsuperheater being connected for series flow of fluid from said fluidheating tubes.

8. A fluid heating unit comprising walls defining an upright vessel ofsubstantially circular horizontalcrosssection, walls including fluidheating tubes defining an upright chamber of substantially rectangularhorizontal cross-section disposed at least in part within said vesseland cooperating with said vessel to define an air flow spacetherebetween, means for supplying a vaporizable fluid to said fluidheating tubes, burner means communicating with said air flow space forsupplying heating gases to said chamber at a pressure at least as greatas a plurality of atmospheres for flow therethrough, means for supplyingair to said air flow space for flow therethrough to said burner means ata pressure at least equal to the gas pressure in said upright chamber,means forming at least a pair of parallel passes at a positiondownstream gas-wise of said burner means for the gases flowing throughsaid chamber, a superheater having at least a portion thereof in one ofsaid parallel passes and including horizontally extending return bendtubes, said superheater being connected for series flow of fluid fromsaid fluid heating tubes, another of said parallel passes being a gasby-pass around the superheater in said one pass, and means forproportioning the total gas flow between said parallel gas passes.

9. A supercharged once-through forced flow fluid heating unit comprisingwalls defining an upright vessel of substantially circular horizontalcross-section, walls including fluid heating tubes defining an uprightchamber of substantially rectangular horizontal cross-section disposedwithin said vessel and cooperating with said ves sel to define an airflow space therebetween, means for supplying a vaporizable fluid to saidfluid heating tubes, burner means communicating with said air flow spacefor supplying heating gases at superatmospheric pressure to the lowerpart of said chamber for flow therethrou-gh,

14 means for supplying air to said air flow space for flow therethroughto said burner means at a pressure at least equal to the gas pressure insaid upright chamber, means forming at least a pair of parallel passesat a positiondownstream gas-wise of said burner means for the gasesflowing through said chamber, a superheater having at least a portionthereof in one of said parallel passes and including horizontallyextending return bend tubes, said superheater being connected for seriesflow of fluid from said fluid heating tubes, another of said parallelpasses being a gas by-pass around the superheater in said one pass, andmeans for proportioning the total gas flow between said parallel gaspasses.

10. A supercharged forced flow fluid heating unit for use in -a binaryelastic fluid power plant including a gas turbine, an air compressordriven by the gas turbine and a vapor turbine, comprising walls definingan upright vessel, Walls including fluid heating tubes defining anupright chamber disposed at least in part Within said Vessel andcooperating with said vessel to define an air flow space therebetween,means for supplying a vaporizable fluid to said fluid heating tubes,burner means communicating with said air flow space for supplyingheating gases at superatmoshpen'c pressure to said chamber for flowtherethrough, means for conducting air from said compressor to said airflow space for flow therethrough to said burner means at a pressure atleast equal to the gas pressure in said upright chamber, means formingat least a pair of parallel passes at a position downstream gas-wise ofsaid burner means for the gases flowing through said chamber, 21superheater having at least a portion thereof in one of said parallelpasses and the remainder upstream gaswise of said parallel passes, saidsuperheater being connected for series flow of fluid from said fluidheating tubes and to the vapor turbine, another of said parallel passesbeing a gas by-pass around the superheater in said one pass, and meansfor maintaining a predetermined vapor temperature to the vapor turbineover a wide range of vapor turbine power output, while maintaining asubstantially constant rate of gas flow at a substantially constant gastemperature to said gas turbine including gas turbine supply means forconducting a portion of the heating gases from said upright chamber at aposition downstream gas-wise of said parallel gas passes to said gasturbine, gas recycling means constructed and arranged to conduct theremainder of the heating gases from a position downstream gas-Wise ofsaid parallel gas passes to said upright chamber at a position upstreamgas-wise of said superheater for mixing with the freshly generatedheating gases, and means for proportioning the total gas flow betweensaid parallel gas passes.

11. A supercharged once-through forced flow fluid heating unit for usein a binary elastic fluid power plant including a gas turbine, an aircompressor driven by the gas turbine and a vapor turbine, comprisingwalls defining an upright vessel, walls including fluid heating tubesdefining an upright chamber disposed within said vessel and cooperatingwith said vessel to define an air flow space therebetween, means forsupplying a vaporizable fluid to said fluid heating tubes, burner meanscommunicating with said air flow space for supplying heating gases atsuperatmospheric pressure to said chamber for flow therethrough, meansfor conducting air from said compressor to said air flow space for flowtherethrough to said burner means at a pressure at least equal to thegas pressure in said upright chamber, means forming at least a pair ofparallel passes at a position downstream gas-Wise. of said burner meansfor the gases flowing through said chamber, a first superheater in saidupright chamber disposed downstream gas-wise of said parallel gaspasses, a second superheater having at least a portion thereof in one ofsaid parallel passes, said fluid heating tubes and said superheatersbeing connected for series flow of fluid to said vapor turbine, anotherof said parallel passes being a gas by-pass around the superheater insaid one r 15 pass, and means for maintaining a predetermined vaportemperature to the vapor turbine over a wide range of vapor turbinepower output, while maintaining a substantially constant rate of gasflow at a substantially constant gas temperature to said gas turbineincluding gas turbine supply means for conducting e -portion of theheating gases from said upright chamber at a position between theparallel g'as passes and the first superheater to said gas turbine, gasrecycling means constructed and airangedlto conduct the remainder of theheating gases from said upright chamber at a position downstreamgas-wise of'said first superheater to said upright chamber at a positionbetween the burner means and said second superheater for-mixing with thefreshly generated heating gases, means for proportioning the total gasflow, between said parallel gas passes.

12. A supercharged once-through forced flow fluid heating unit for usein a binary elastic fluid power plant including a gas turbine, an'aircoin'pressor'driven by the gas turbine and a vapor turbine, comprisingwalls defining an upright vessel, walls including fluid heating tublesdefining an uprightfchamber disposed within said" vessel andcooperatingwith'said vessel to define an air flow space therebetween,means for, supplying a vaporizable fluid to said fluid heating tubes,burner means communicating with oneend of said air flow space forsupplying heating gases at superatmospheric pressure to said. chamberfor flow therethrough, means-forming at least a pair of parallel passes.at :a'position downstream gas-wise'of said burner means for the gasesflowing through said chamber, a vertically elongated vessel disposedlaterally adjacent said upright vessel, an'upright gas pass disposedwithin said vertically elongated vessel, said upright gas pass ing withsaid upright chamber at aposition-downstream having its inlet endcommunicate gas-wise of said parallel gas passes and cooperating with,

said vertically elongated vessel to define anair flow zone communicatingat one end with the opposite end of said airflow space, means forconducting air from said compressor to the opposite end of said air flowzone for flow therethrough to said air flow space and thence to saidburner means at a pressure at least equal to the gas pressure in saidupright chamber, a first superheater in said upright gas pass, a secondsuperheater having at least a portion thereof in one of said parallelpasses, said fluid heating tubes and said superheaters being connectedfor series flow of fluid to the vapor turbine, an? other of saidparallel passes being a. gas by-pass around the superheater in said onepass, and means for maintaining a predetermined vapor temperature to thevapor turbine over a wide range of vapor turbine power output, whilemaintaining a substantially constant rate of gas flow at a substantiallyconstant gas temperature to said gas turbine including gas turbinesupply means for conducting a portion of the heating gases from saidupright chamber at a position between the parallel gas passes and thefirst superheaterito said gas turbine,

the remainder of the heating gases discharging to said upright gas pass,gas recycling means constructed and arranged to conduct the remainder ofthe heating .gases from said upright gas pass at a position downstreamgaswise of said first superheater to said upright chamber at Ya positionbetween the burner means and said second superheater for mixing with thefreshly generated heating gases, and means for proportioning the totalgas flow between said parallel gas passes.

13. A supercharged forced flow fluid heating unit for use in a binaryelastic fluid power plant including a gas turbine, an air compressordriven by the gas turbine and a vapor turbine having high and lowpressure stages, comprising walls including fluid heating tubes definingan upright chamber, means for supplying a vaporizable fluid to saidfluid heating tubes, burner means for supplying' heating'gases atsuperatmospheric pressure to said- 16 parallel passes at a positiondownstream gas-wise of said burner means for the gases flowing throughsaid chamber, a superheater having at least a portion thereof in one ofsaid parallel passes, said superheater being connected for series flowof fluid from said fluid heating tubes and to the high pressure stage ofsaid turbine, a reheater in another of said passes and connected forseries flow of fluid from the, high pressure stage of said vapor turbineand to the low pressure stage of said vapor turbine, the third passbeing a gas bypass around the superheater in said one pass and thereheater, and means for maintaining predetermined vapor temperatures tothe highand low pressure stages of said vapor turbine over a wide rangeof vapor turbine power output, whilemaintaining a substantially constantrate of gas flow at a substantially constant gas temperature to saidgas, turbine including gas turbine supply means for conducting heatinggases from a position downstream, gas-wise of said parallel gas passesto said gas turbine, gas recycling means constructed and arranged toconduct heating gasm from fa position down-stream gas-wise of saidparallel gas passes tosaid upright chamber at a position upstreamgas-wise of said gases, and means for proportioning the total gas flowbetween said parallel gas passes.

' 14. A supercharged forced flow fluid heating unit for use in a binaryelastic fluid power plant including a gas turbine, an air compressordriven by the gasturbine and a vapor turbine having high and lowpressure stages, comprising walls defining an upright vessel, wallsincluding fluid heating tubes defining an upright chamber dis posed atleast in part within said vessel and cooperating with said vessel todefine an air flow space therebetween, means for supplying a vaporizablefluid to said fluid heating tubes, burner means communicating with saidair flow space for supplying heating gases at superatmospheric pressureto'said chamber for flow therethrough, means for conducting air fromsaidcompressor to' said air flow space for flow therethrough to saidburner means at a pressure at least-equal to the gas pressure in saidupright chamber, means forming three parallel passes at a positiondownstream gas-wise of said burner means for the gases flowing throughsaid chamber, a superheater having at least a portion thereof in one ofsaid parallel passes, said superheater being connected for series flowof fluid from said fluid heating tubes and to the high pressure stage ofsaid turbine, a reheater in another of said passes and connected forseries flow of fluid from the high pressure stage of said vapor turbineand to the low pressure stage of said vapor turbine, the third passbeing a gas by-pass around the superheater in said one pass and thereheater, gas turbine supply means for conducting heating gases from aposition downstream gas-wise of said' parallel gas passes to said gasturbine, gas recycling means constructed and arranged to conduct heatinggases from a position downstream gas-wise of said parallel gas passes tosaid upright chamber at a position upstream gas-wise of said superheaterfor mixing with the freshly generated heating gases, and damper meansfor proportioning the total gas flowbetween said parallel gas passes;

15. A supercharged once-through forced flow-fluid heating unit for usein a binary elastic fluid power plant including a gas turbine, an aircompressor driven by the gas turbine and a vapor turbine having high andlow pressure stages, comprising walls defining an-upright to said airflow space for flow therethrough to said burner means at a pressure atleast equal to the gas pressure in said upright chamber, means formingthree parallel passes at a position downstream gas-wise of said burnermeans for the gases flowing through said chamber, a first superheater insaid upright chamber disposed downstream gas-wise of said parallel gaspasses, a second superheater having a portion thereof in one of saidparallel passes and the remainder upstream gaswise of said parallelpasses, said fluid heating tubes and said superheaters being connectedfor series flow of fluid to the high pressure stage of said vaporturbine, a reheater in another of said passes and connected for seriesflow of fluid from the high pressure stage of said vapor turbine and tothe low pressure stage of said vapor turbine, the third pass being a gasbypass around the superheater in said one pass and the reheater, andmeans for maintaining predetermined vapor temperatures to the high andlow pressure stages of said vapor turbine over a wide range of vaporturbine power output, while maintaining a substantially constant rate ofgas flow at a substantially constant gas temperature to said gas turbineincluding gas turbine supply means for conducting heating gases fromsaid upright chamber at a position between the parallel gas passes andthe reheater to said gas turbine, gas recycling means constructed andarranged to conduct heating gases from said upright chamher at aposition downstream gas-wise of said first superheater to said uprightchamber as tempering gases at a position between the burner means andsaid second superheater for mixing with the freshly generated heatinggases, and damper means for proportioning the total gas flow betweensaid parallel gas passes.

16. The method of operating a binary elastic fluid power plantcomprising a gas turbine, an air compressor driven by the gas turbine,and a vapor generating and superheating unit having a fluid cooledheating gas receiving zone, means supplying freshly generated highpressure heating gases to the gas receiving zone, a pair of parallel gaspasses beyond said gas receiving zone, and a superheater having at leasta portion thereof in one of said parallel gas passes and subject to theheating gas flow after loss of heat therefrom in vapor generation, theother of said parallel gas passes being a gas bypass around thesuperheater in said one gas pass, said method comprising the steps ofpassing the superheated vapor from the superheater to the vapor turbine,maintaining a predetermined vapor temperature to the vapor turbine overa wide range of vapor turbine output, while maintaining a substantiallyconstant rate of gas flow at a substantially constant gas temperature tosaid gas turbine by withdrawing heating gases from a position downstreamgas-wise of said parallel gas passes and discharging the withdrawn gasesinto said gas receiving zone at a position upstream gas-wise of saidparallel gas passes for mixing with the freshly generated heating gases,

proportioning the flow of gases thus mixed between said parallel gaspasses, conducting heating gases from a position downstream gas-wise ofsaid parallel gas passes to said gas turbine, decreasing the rate ofsupply of freshly generated gases as the rate of vapor turbine poweroutput decreases, and passing high pressure air from said compressor tosaid high pressure heating gas supply means.

17. The method of operating a binary elastic fluid power plantcomprising a gas turbine, an air compressor driven by the gas turbine,and a vapor generating and superheating unit having a fluid cooledheating gas receiving zone, means supplying freshly generated highpressure heating gases to the gas receiving zone, a pair of parallel gaspasses beyond said gas receivin zone, and a superheater having at leasta portion thereof in one of said parallel gas passes and subject to theheating gas flow after loss of heat therefrom in vapor generation, theother of said parallel gas passes being a gas bypass around thesuperheater in said one gas pass, said method comprising the steps ofpassing the superheated vapor from the superheater to the vapor turbine,maintaining a predetermined vapor temperature to the vapor turbine overa wide range of vapor turbine output, while maintaining a substantiallyconstant rate of gas flow at a substantially constant gas temperature tosaid gas turbine by withdrawing heating gases from a position downstreamgas-wise of said parallel gas passes and discharging the withdrawn gasesinto said gas receiving zone at a position upstream gas-wise of saidparallel gas passes for mixing with the freshly generated heating gases,decreasing the rate of flow of the gases so Withdrawn as the rate ofvapor turbine power output decreases, conducting the gases thus mixedthrough said parallel gas passes to a common gas mixing zone therebeyondand proportioning the flow of gases through the parallel gas passes sothat the temperature thereof upon mixing in the common gas mixing zoneremains substantially constant as the rate of vapor turbine power outputdecreases, supplying the gas turbine with heating gases from said commongas mixing zone at a substantially constant rate as the rate of vaporturbine power output decreases, decreasing the rate of supply of freshlygenerated gases as the rate of vapor turbine power output decreases, andpassing high pressure air from said compressor to said high pressureheating gas supply means at a substantially constant rate as the rate ofvapor turbine power output decreases.

References Cited in the file of this patent UNITED STATES PATENTS1,948,538 Noack Feb. 27, 1934 2,184,845 Noack Dec. 26, 1939 2,361,812Barnes Oct. 31, 1944 2,628,598 Van Brunt Feb. 17, 1953 2,776,647 HawleyJan. 8, 1957

